The chief executive of Total, one of Europe's biggest oil groups, the former interior minister Charles Pasqua, the Swiss oil trader Vitol and a former French ambassador to the UN were among the 20 defendants acquitted.

They were accused of participating in a corrupt system of bribery, complicity, kickbacks and influence peddling which profited from the international community's efforts to get humanitarian aid to ordinary Iraqis under Saddam's rule.

The vast oil-for-food programme, which operated from 1996 to 2003, was designed to ease the plight of Iraqis during sanctions imposed after the first Gulf war. It allowed Iraq to sell some of its oil in exchange for humanitarian supplies and equipment. But a series of investigations claimed it was quickly abused by UN staff, Hussein and western and Middle Eastern companies, who made millions from a parallel web of illegal kickbacks that may have involved as many as 2,200 companies in up to 66 countries.

In 2005, an independent inquiry led by the former US Federal Reserve chairman Paul Volcker disclosed a system of kickbacks and payments to prominent individuals with access to Iraqi oil described as "wholesale corruption" across a large number of countries.

The French trial took place earlier this year after repeated delays and despite the state prosecutor's office having advised that the case should not go to court. After deliberation, the judges dismissed all corruption charges against all defendants.

The French energy giant Total had faced charges of bribery, complicity and benefiting from influence-peddling, which it had denied. Its chief executive, Christophe de Margerie, was accused of complicity in the misuse of corporate assets and risked up to five years in jail and a heavy fine. Total's lawyer said the company was happy to be "totally cleared". Pasqua, who served in two rightwing governments, criticised the "inanity of the slanderous accusations brought against me".